debilitating

Something that's debilitating seriously affects someone or something's strength or ability to carry on with regular activities, like a debilitating illness.

Debilitating comes from the Latin word debilis, meaning "weak." That's why you'll often see the adjective used to describe illness. After all, serious diseases weaken the body. Other things that can be debilitating are those that can stop you from reaching a goal, like a debilitating snow storm that forces you to stay home, or debilitating shyness that keeps you from reaching out to the people you want to meet.